The long term goal of our research is to define the functional roles of src and myc gene products in Drosophila development. We have isolated recombinant clones containing Drosophila genomic sequences that are related to the oncogenes v-src and v-myc. These sequences have been employed as hybridization probes to measure the levels of src and myc RNA sequences throughout development. Both src and myc RNA sequences are present in preblastoderm embryos, the RNA's disappear by late embryogenesis and are present again at specific times during pupal development. The presence of these RNA sequences in preblastoderm embryos suggests that they are of maternal origin. In the case of myc, the embryo RNA species are present in ovaries but absent from the other male and female adult tissues. The specific aims of this proposal are: 1) To determine the sequence relationships of the Drosophila src and myc genes and the corresponding vertebrate genes. We will subject genomic and cDNA clones to nucleotide sequence analyses so as to define the homology between the different members of the Drosophila src and myc gene families and the vertebrate genes. 2) To analyze src and myc expression during oogenesis and embryogenesis. In situ hybridizations to histological sections of different developmental stages will allow us to analyze the localization of src and myc transcripts to specific cells and tissues. The temporal pattern of src protein synthesis will be determined by immunoprecipitation of labeled protein. The organization of src protein will be determined by fluorescent antibody staining of histological sections. 3) To apply genetic techniques to the study of src and myc function. Our working hypothesis is that mutations in src and myc genes will have a maternal effect phenotype. We will determine the chromosomal loci encoding the cloned genes by in situ hybridizations to polytene chromosomes. These loci will be compared to those encoding known maternal effect mutations. P-element-mediated transformation techniques will be employed to test whether the candidate mutations correspond to one of the cloned src or myc genes.